It is the first process (server) to be started based on hostname, port, customer hardware key, and executable path.
Its main purpose is to load balance the system (when more than one Dialog instance is configured)
It is also used to handle the lock requests that are initiated from dialog instances. There will be only one message server in the entire system. It is monitored in SMMS (MSMON or SAPMMC).
ST07 is used to identify the workload on the system based on functions on the system. It is used to identify which functional are is consuming time (response time), which functional are is swapping out the content from buffer, number of instances, load on the system/instance, number of processes and number of users.
It is a motivation to deploy additional instances/configure load balancing based on the load generated by functional area.
CONFIGURE LOAD BALANCING
It is configured when more than one instance is available in the landscape. Identify the functional load in the ST07 and based on that define logon load groups.
Example-:5000 users company has 22 instances.
There are 1000 users who work on sales, 1000 on finance, 1000 on material procurement, 50 on HR, 500 on production process, 500 on logistics and remaining 950 on miscellaneous.
Identifies the total number of Dialog steps based on functional modules. Allocate an instance for every 250 people.(Don’t load on CENTRAL INSTANCES)
Define logon group SALES in SMLG and allocate 4 instances
Define logon group MATERIAL in SMLG and allocate 4 instances
Define logon group FINANCE in SMLG and allocate 4 instances
Define logon group LOGISTICS in SMLG and allocate 3 instances
Define logon group HR & PRODCUTION in SMLG and allocate 3 instances
Define logon group MISCELLANEOUS in SMLG and allocate 3 instances
Keep it as free as possible to monitor all the instances.
Define SMLG and define the above groups and assign.
MECHANISM OF LOAD BALANCING
- User submits the requests to logon group instead of application server and instance number.
- The user requests communicate with message server using message server host/message server services and system identifier.
Name of the message server |||||3600/TCP |||DEV|PRD|QAS
Etc|hosts etc|services sapmsg.ini
The above details are mandatory to be maintained on the all presentation server.
- Message server maintains the favorite server and favorite time in SMLG–>Go to–>System diagnosis–>Message server status area.
- Message server route the request to favorite dispatcher in that group based on think time and answer time of message server.
Similarly, RZ12 is used for background or RFC communication.
Configuring GUI/Presentation server to use Logon Groups-:
Select the logon group server–>specify the description–>Specify message server name–>specify logon group and save the entry.
RFC server groups for background processing-:
Execute RZ11–> Define server groups and assign the instances. These are used by defining RFC connections using the option load balancing.
Message server listens on port 3600 and requires sapmsg.ini on all the presentation servers.
Message server is also used to provide locks to the dialog processes which are coming from other than Central Instance.
Very Basic but very informative. Explained well with good example.